JP2002053346A - Glass chopped strand - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a glass chopped strand comprising alkali-proof glass fibers, easy to split in a cement slurry and usable even in a cold district. SOLUTION: The glass chopped strand contains >=14 mass% ZrO2 and >=10 mass% alkali metal oxide and the surface of the strand has been treated with a sizing agent containing a polyalkylene oxide having <=3% urethane bonds in its molecular chain and having a molecular weight of >=1,000.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a glass chopped strand suitable as a reinforcing material for cement-based materials used in the fields of construction and civil engineering.

[0002]

_2. Description of the Related Art Alkali-resistant glass fibers containing 14% by mass or more of ZrO ₂ have been known as glass fibers having excellent alkali resistance. Glass chopped strands are cut by cutting this glass fiber into a predetermined length. It is generally recognized that a sufficient reinforcing effect can be obtained by preparing and using this as a reinforcing material for a cement-based material by defibrating in a cement slurry.

[0003] ZrO ₂ which is a constituent of this glass fiber
Is very strong against alkaline substances, and contains a large amount (specifically, 14% by mass or more) of glass to improve the alkali resistance of the glass.

However, such a glass containing a large amount of ZrO ₂ is very difficult to melt, so that a large amount of alkali metal oxides (Li ₂ O, Na ₂ O, K ₂ O) is used as a flux (specifically, such a glass). Specifically, the melting property of the glass is improved by containing 10% by mass or more.

[0005]

The manufacturing process of glass chopped strands uses an applicator to apply a glass filament (glass single fiber) obtained by spinning molten glass from a bushing having hundreds to thousands of nozzles. After applying the sizing agent, they are aligned and wound up on a paper tube to form a cake, a spinning process, drying the cake, and a drying process for forming a film of the sizing agent on the surface of the glass fiber, from the outer layer of the cake. It consists of a processing step of cutting the strand while unwinding it to produce a glass chopped strand.

[0006] As described above, immediately after being spun, the glass single fiber is surface-treated with a sizing agent (a sizing agent).
Usually, stable polyvinyl acetate resin or acrylic resin is used as a material for the sizing agent of alkali-resistant glass fiber. However, when this alkali-resistant glass fiber is cut to produce a glass chopped strand and used as a reinforcing material for a cement-based material, if the stirring time for disintegrating the glass chopped strand in a cement slurry is short, Since the defibration state becomes uneven and the reinforcing effect tends to be insufficient, the stirring time needs to be extremely long.

A wet chopped strand containing a large amount of water (specifically, about 7% by mass) is excellent in fibrillation in a cement slurry, but is not suitable for use in a cold region because it freezes in a cold region. . That is, it cannot be put into the cement slurry.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a glass chopped strand made of alkali-resistant glass fiber which can be easily defibrated in a cement slurry and can be used even in a cold region.

[0009]

As a result of repeating various experiments to achieve the above object, the present inventor has found that the reason why the conventional glass chopped strand has a poor fibrillation property in cement slurry is glass fiber. A large amount of alkali components eluted from the sizing agent, and this reacted with the sizing agent to form a tough film on the surface, which was found to be the reason for inhibiting the disintegration of the glass chopped strand, and led to the present invention. Was.

That is, the glass chopped strand of the present invention is a glass chopped strand containing 14% by mass or more of ZrO ₂ and 10% by mass or more of an alkali metal oxide and having its surface treated with a sizing agent. The sizing agent is characterized by containing a polyalkylene oxide having a molecular weight of 1000 or more and having a urethane bond of 3% or less in a molecular chain.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION The glass chopped strand of the present invention is made of glass fibers containing 14% by mass or more of ZrO ₂ and therefore has excellent alkali resistance. Glass fiber is hardly eroded by an alkaline substance in a cementitious material even if it is used as a reinforcing material for cement. Therefore, the tensile strength of the glass fiber is not easily reduced by the alkaline substance, and the reinforcing effect can be maintained for a long period of time. Also Z
The lowering of the melting property of the glass due to rO ₂ is compensated by containing 10% by mass or more of the alkali metal oxide.

The specific composition of the alkali-resistant glass fiber suitable for the present invention is, in mass%, 54 to 65% of SiO ₂ , Zr
O ₂ 14 to 25%, Li ₂ O 0 to 5%, Na ₂ O 1
0-17%, K ₂ O 0-8%, RO (where R is
Mg, Ca, Sr, Ba, Zn) 0-10%,
TiO ₂ 0 to 7%, Al ₂ O ₃ 0 to 2%, more preferably, in mass%, SiO ₂ 57 to 64%, Zr
_{O 2 18~24%, Li 2 O} 0.5~3%, Na 2 O
_{11~15%, K 2 O 1~5%} , RO 0.2~8
%, TiO ₂ 0.5~5%, an Al ₂ O ₃ 0~1%.

In the present invention, the sizing agent applied to the surface of the glass fiber contains a polyalkylene oxide having a molecular weight of 1000 or more and having a urethane bond of 3% or less in a molecular chain. Since it does not easily react with the alkali component therein, a tough film is not formed on the glass fiber surface. Therefore, the glass chopped strand formed from this glass fiber is easily defibrated in the cement slurry, and a high-strength cement-based material can be obtained in a short working time (stirring time).

However, if the ratio of urethane bonds in the molecular chain of the polyalkylene oxide is more than 3% or the molecular weight is less than 1,000, the effect of improving the defibrating property of the glass chopped strand cannot be obtained. .

Further, if the amount of the polyalkylene oxide having a molecular weight of 1000 or more and having a urethane bond of 3% or less in the molecular chain is too large, the glass chopped strand is liable to fuzz before being charged into the cement slurry. Not preferred. Therefore, its content is 1.0 to 6.0% by mass in terms of solid content, preferably 1.5 to 6.0% by mass.
4.5% by mass.

In the present invention, when the moisture content of the glass chopped strand is high, the glass chopped strand freezes when the temperature drops to 0 ° C. or less in a cold region and cannot be used. It is preferable to set the following. Incidentally, the water content of the glass chopped strand can be adjusted by changing the spray amount of the cooling water to the glass fiber, the water application amount from the sizing agent, and the aging and drying conditions of the cake, and is measured based on the method of JIS R3420. It is possible.

Furthermore, as described above, since the cake has a form in which a large number of glass fibers are wound in a bundled state, the unwinding property when unwinding the glass fiber is improved, and the generation of fuzz and the like occurs. Is very important in improving the cutting workability during the production of glass chopped strands.

In order to improve the unwinding property of the glass fiber, it is preferable to include a polyamine-based activator such as a polyalkylpolyaminealkylamide derivative in the sizing agent. However, it is not preferable to include a large amount of the polyamine-based activator, since the glass fiber becomes tacky and a gum-up easily occurs. By the way, gum up is a sizing agent that has adhered to the surface of glass fiber adhered to the contact parts of various jigs used in the processing process by friction. Becomes Therefore, it is desirable that the polyamine-based activator is contained in an amount of 0.01 to 0.5% by mass, preferably 0.03 to 0.3% by mass in terms of solid content.

When the sizing agent contains a silane coupling agent such as amino silane, epoxy silane, methacryl silane, vinyl silane or ureido silane,
Although it is preferable because breakage of the glass fiber can be prevented, if it is contained in a large amount, the fibrillation in the cement slurry is reduced. Therefore, the silane coupling agent is used in an amount of 0.05 to 1.0% by mass, preferably 0.1 to 0.
It is desirable to contain 5% by mass.

Further, when a polyvinyl acetate resin is contained in the sizing agent, the convergence of the glass chopped strand is improved and the workability is improved, but it is preferable. The defibration property decreases. Therefore, it is desirable that the polyvinyl acetate resin is contained in a solid content of 1.0 to 5.0% by mass, preferably 2.0 to 4.0% by mass.

Such a sizing agent prevents the surface of the glass fiber formed in the spinning process from being damaged or imparts a binding property to the glass strand, thereby causing generation of fluff and yarn breakage in the processing process. It has the function of preventing and easily defibrating the glass fiber in the cement slurry and dispersing it uniformly in the cement slurry, and the adhesion rate of the sizing agent to the glass fiber is 0.3 to
1.0% by weight is suitable. That is, if the adhesion ratio is less than 0.3% by mass, the above effect is poor, and
When the content is more than the mass%, the product cost increases. Incidentally, the adhesion rate of the sizing agent can be adjusted by changing the solid content of the sizing agent and the number of revolutions of the applicator in the spinning process, and can be measured based on the method of JIS R3420.

[0022]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the glass chopped strand of the present invention will be described in detail based on embodiments.

Table 1 shows examples (samples Nos. 1 to 4) of the glass chopped strand of the present invention, and Table 2 shows comparative examples (samples Nos. 5 and 6).

[0024]

[Table 1]

[0025]

[Table 2]

No. in the table Each of the samples 1 to 6 was prepared as follows.

First, each sizing agent having each component shown in the table is prepared, applied to a single glass fiber (diameter: 18 μm) spun from a bushing nozzle using an applicator, and then 2,000 pieces are aligned and then formed into a paper tube. The cake was made by winding. Next, the cake was dried and then cut while unwinding the glass strand from the outer layer of the cake to obtain a 13 mm glass chopped strand. In addition, the composition of the glass fiber is SiO ₂ 6 by mass%.
1%, ZrO ₂ 19.5%, Li ₂ O 1.5%, Na ₂
O 12.3%, K ₂ O 2.6%, CaO 0.5
%, TiO ₂ 2.6%, and the polyalkylene oxide in the sizing agent used had 2% urethane bonds in the molecular chain and had the molecular weight shown in the table. Further, the sizing agent adhesion rate and the water content of the glass chopped strand were adjusted to be the values shown in the table.

These glass chopped strands are
After 3% by weight was mixed into a cement slurry composed of 100 parts by mass of cement and 40 parts by mass of water, the mixture was put into a stirrer to prepare 4 parts by mass.
The mixture was stirred at a speed of 00 rpm, and the time until the glass chopped strand was completely defibrated was measured, and the results are shown in the table.

As is clear from the table, the N
o. Since each of Samples 1 to 4 has a short defibration time of 60 seconds or less, it can be understood that the samples have excellent defibration properties.

On the other hand, in Comparative Example No. Sample No. 5 used a sizing agent having a polyalkylene oxide molecular weight of 500, and thus had a long defibration time of 120 seconds. No. The sample No. 6 used a sizing agent containing an acrylic resin instead of a polyalkylene oxide, so that a tough film was formed on the surface of the glass fiber and the glass chopped strand was defibrated even after stirring for 10 minutes. I never did.

[0031]

As described above, the glass chopped strand of the present invention has excellent alkali resistance, and the alkali component in the glass reacts with the sizing agent without forming a tough film on the fiber surface. Since it is easily defibrated in a cement slurry, it is particularly suitable as a reinforcing material for a cement-based material produced by defibrating a glass chopped strand in a cement slurry.

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Claims (4)

[Claims] 1. A glass chopped strand containing at least 14% by mass of ZrO ₂ and at least 10% by mass of an alkali metal oxide and having its surface treated with a sizing agent, wherein the sizing agent is contained in a molecular chain. A glass chopped strand comprising a polyalkylene oxide having a urethane bond of 3% or less and a molecular weight of 1000 or more. 2. The glass chopped strand according to claim 1, wherein the water content is 0.5% by mass or less. 3. A sizing agent comprising a polyalkylene oxide having a molecular weight of 1000 or more and having a urethane bond of 3% or less in a molecular chain in a solid content notation of 1.0 to 6.0% by mass,
It is characterized by containing 0.01 to 0.5% by mass of a polyamine-based activator, 0.05 to 1.0% by mass of a silane coupling agent, and 1.0 to 5.0% by mass of a polyvinyl acetate resin. The glass chopped strand according to claim 1. 4. The glass chopped strand according to claim 1, wherein the glass chopped strand is used as a reinforcing material for a cement-based material after being defibrated in a cement slurry.